Network Working Group R. Bush
Internet-Draft Internet Initiative Japan
Intended status: BCP March 10, 2011
Expires: September 11, 2011
RPKI-Based Origin Validation Operationdraft-ietf-sidr-origin-ops-06
Abstract
Deployment of RPKI-based BGP origin validation has many operational
considerations. This document attempts to collect and present them.
It is expected to evolve as RPKI-based origin validation is deployed
and the dynamics are better understood.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 11, 2011.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
Bush Expires September 11, 2011 [Page 1]

Internet-Draft RPKI-Based Origin Validation Operation March 20111. Introduction
RPKI-based origin validation relies on widespread propagation of the
Resource Public Key Infrastructure (RPKI) [I-D.ietf-sidr-arch]. How
the RPKI is distributed and maintained globally is a serious concern
from many aspects.
The global RPKI is in very initial stages of deployment, there is no
root trust anchor, initial testing is being done by the IANA and some
RIRs, and there is a technical testbed. It is thought that origin
validation based on the RPKI will be deployed incrementally over the
next year to five years.
Origin validation only need be done by an AS's border routers and is
designed so that it can be used to protect announcements which are
originated by large providers, upstreams and downstreams, and by
small stub/enterprise/edge routers.
Origin validation has been designed to be deployed on current routers
without significant hardware upgrade. It should be used by everyone
from large backbones to small stub/entetprise/edge routers.
RPKI-based origin validation has been designed so that, with prudent
local routing policies, there is little risk that what is seen as
today's normal Internet routing is threatened by imprudent deployment
of the global RPKI, see Section 5.
2. Suggested Reading
It is assumed that the reader understands BGP, [RFC4271], the RPKI,
see [I-D.ietf-sidr-arch], the RPKI Repository Structure, see
[I-D.ietf-sidr-repos-struct], ROAs, see [I-D.ietf-sidr-roa-format],
the RPKI to Router Protocol, see [I-D.ietf-sidr-rpki-rtr], RPKI-based
Prefix Validation, see [I-D.ietf-sidr-pfx-validate], and Ghostbuster
Records, see [I-D.ietf-sidr-ghostbusters].
3. RPKI Distribution and Maintenance
The RPKI is a distributed database containing certificates, CRLs,
manifests, ROAs, and Ghostbuster Records as described in
[I-D.ietf-sidr-repos-struct]. Policies and considerations for RPKI
object generation and maintenance are discussed elsewhere.
A local valid cache containing all RPKI data may be gathered from the
global distributed database using the rsync protocol and a validation
tool such as rcynic.
Bush Expires September 11, 2011 [Page 3]

Internet-Draft RPKI-Based Origin Validation Operation March 2011
Validated caches may also be created and maintained from other
validated caches. Network operators SHOULD take maximum advantage of
this feature to minimize load on the global distributed RPKI
database.
As RPKI-based origin validation relies on the availability of RPKI
data, operators SHOULD locate caches close to routers that require
these data and services. A router can peer with one or more nearby
caches.
For redundancy, a router SHOULD peer with more than one cache at the
same time. Peering with two or more, at least one local and others
remote, is recommended.
If an operator trusts upstreams to carry their traffic, they SHOULD
also trust the RPKI data those upstreams cache, and SHOULD peer with
those caches. Note that this places an obligation on those upstreams
to maintain fresh and reliable caches.
A transit provider or a network with peers SHOULD validate origins in
announcements made by upstreams, downstreams, and peers. They still
SHOULD trust the caches provided by their upstreams.
Before issuing a ROA for a block, an operator MUST ensure that any
sub-allocations from that block which are announced by other ASs,
e.g. customers, have correct ROAs in play. Otherwise, issuing a ROA
for the super-block will cause the announcements of sub-allocations
with no ROAs to be Invalid.
An environment where private address space is announced in eBGP the
operator MAY have private RPKI objects which cover these private
spaces. This will require a trust anchor created and owned by that
environment, see [I-D.ietf-sidr-ltamgmt].
Operators issuing ROAs may have customers announce their own prefixes
and ASs into global eBGP but who do not wish to go though the work to
manage the relevant certificates and ROAs. The operator SHOULD
provision the RPKI data for these customers just as they provision
many other things for them.
4. Within a Network
Origin validation need only be done by edge routers in a network,
those which border other networks/ASs.
A validating router will use the result of origin validation to
influence local policy within its network, see Section 5. In
Bush Expires September 11, 2011 [Page 4]

Internet-Draft RPKI-Based Origin Validation Operation March 2011
deployment this policy should fit into the AS's existing policy,
preferences, etc. This allows a network to incrementally deploy
validation capable border routers.
eBGP speakers which face more critical peers or up/downstreams would
be candidates for the earliest deployment. Validating more critical
received announcements should be considered in partial deployment.
5. Routing Policy
Origin validation based on the RPKI merely marks a received
announcement as having an origin which is Valid, NotFound, or
Invalid. See [I-D.ietf-sidr-pfx-validate]. How this is used in
routing SHOULD be specified by the operator's local policy.
Local policy using relative preference is suggested to manage the
uncertainty associated with a system in early deployment, applying
local policy to eliminate the threat of unroutability of prefixes due
to ill-advised certification policies and/or incorrect certification
data. E.g. until the community feels comfortable relying on RPKI
data, routing on Invalid origin validity, though at a low preference,
MAY occur.
As origin validation will be rolled out incrementally, coverage will
be incomplete for a long time. Therefore, routing on NotFound
validity state SHOULD be done for a long time. As the transition
moves forward, the number of BGP announcements with validation state
NotFound should decrease. Hence an operator's policy SHOULD NOT be
overly strict, preferring Valid announcements, attaching a lower
preference to, but still using, NotFound announcements, and dropping
or giving very low preference to Invalid announcements.
Some may choose to use the large Local-Preference hammer. Others
might choose to let AS-Path rule and set their internal metric, which
comes after AS-Path in the BGP decision process.
When using a metric which is also influenced by other local policy,
the operator should be careful not to create privilege upgrade
vulnerabilities. E.g. if Local Pref is set depending on validity
state, be careful that peer community signaling MAY NOT upgrade an
invalid announcement to valid or better.
Announcements with Valid origins SHOULD be preferred over those with
NotFound or Invalid origins, if the latter are accepted at all.
Announcements with NotFound origins SHOULD be preferred over those
with Invalid origins.
Bush Expires September 11, 2011 [Page 5]

Internet-Draft RPKI-Based Origin Validation Operation March 2011
Announcements with Invalid origins MAY be used, but SHOULD be less
preferred than those with Valid or NotFound.
6. Notes
Like the DNS, the global RPKI presents only a loosely consistent
view, depending on timing, updating, fetching, etc. Thus, one cache
or router may have different data about a particular prefix than
another cache or router. There is no 'fix' for this, it is the
nature of distributed data with distributed caches.
There is some uncertainty about the origin AS of aggregates and what,
if any, ROA can be used. The long range solution to this is the
deprecation of AS-SETs, see [I-D.wkumari-deprecate-as-sets].
Operators which manage certificates SHOULD have RPKI Ghostbuster
Records (see [I-D.ietf-sidr-ghostbusters]), signed indirectly by End
Entity certificates, for those certificates on which others' routing
depends for certificate and/or ROA validation.
7. Security Considerations
As the BGP origin is not signed, origin validation is open to
malicious spoofing. It is only designed to deal with inadvertent
mis-advertisement.
Origin validation does not address the problem of AS-Path validation.
Therefore paths are open to manipulation, either malicious or
accidental.
The data plane may not follow the control plane.
Be aware of the class of privilege escalation issues discussed in
Section 5 above.
8. IANA Considerations
This document has no IANA Considerations.
9. Acknowledgments
The author wishes to thank Rob Austein, Steve Bellovin, Pradosh
Mohapatra, Chris Morrow, Sandy Murphy, Keyur Patel, Heather and Jason
Schiller, John Scudder, Maureen Stillman, and Dave Ward.
Bush Expires September 11, 2011 [Page 6]